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By Suzanne Smith, Frank C. Fantauzzo

Introduction America's workforce is the heart of the nation's economy. The health of its members is a matter of national priority. Statistics show that the most common cause of job difficulties is excess use of alcohol or other drugs. Up to 75% of these troubled employees can be returned to productive careers at little expense and with great benefit to their industries. Of the 1.5 million private corporations in the US, only about 500 have alcohol treatment programs. Even fewer have drug abuse programs. It is time that the myths and prejudices surrounding alcohol and drug abuse are dispelled and help is offered. Corporations and labor unions are now finding that programs to treat these diseases benefit both the employees and the industry. The employee derives health and job security. The company sees increased productivity and decreased costs in sick pay and absenteeism. Unfortunately, three-fourths of the nation's 90.5 million workers are employed in establishments of fewer than 500 employees. In these settings, it is unlikely that either management or the unions will take the initiative in developing programs. Alcohol alone affects the health and productivity of nearly 8% of any workforce. This translates to more than 5 million employees in small business. These workers present an opportunity and a challenge. Alcohol abuse costs the nation nearly $116 billion annually. Seventy billion dollars is attributed to lost production. Medical expenditures related to alcohol are estimated to be nearly $13 billion. The National Institute on Drug Abuse (NIDA) estimates the cost of substance abuse to industry to be in excess of $4 billion a year. In addition to its economic impact, substance abuse has serious personal and social consequences. The mining industry experiences the same exposure as other industries to alcohol, drug abuse, and other employee problems. However, the existence of these problems poses special hazards because of the unique conditions found in mining. Mining has many safety and health hazards. Employees must have full control of their faculties and give full attention to the tasks at hand. Designing employee assistance programs An Employee Assistance Program is a cost-effective, confidential, early intervention system. It is designed to help employees

Jan 11, 1987

By M. G. Ayat, J. W. Leonard

Introduction Coal preparation plants are continuously losing clean coal in their refuse and contaminating their clean coal product with impurities. This is due to the lack of a system by which the immediate efficiency of the cleaning operation can be determined at any given time. Moreover, the advantage of developing tagging/ tracing techniques would be a reduction in the time and money spent in evaluating the performance of advanced cleaning techniques. Currently, conventional sampling and testing, on-line analyses, and computer information systems are the major tools with which engineers analyze and control the efficiency of processing plants. Conventional sampling and testing is an effective analysis technique but it is slow. On-line analysis provides information on quality parameters rapidly, but these parameters do not provide all of the necessary information. The use of tagged particles in coal preparation plants may provide the necessary link between diagnosis and the application of computers to process control. In this work, a novel technique that uses tagged particles to generate partition data is presented (Leonard et al., 1982). Individually prepared tagged particles are added to the feed and detected in the product or refuse port of specific gravity based processes. Providing that a computer can interpret the output of a detection device and trace particles with predetermined physical properties through the coal preparation plant and that the trace particles actually represent desired raw material, sufficient partition data can be provided for computer analyses and control of processing efficiency. Coal tagging technique The use of tagged particles in coal preparation operations are in the early stages of development. Though there is a brief history of particle tracing in the mineral processing industry (Gardner et al., 1986; Foreman and Amundson, 1976; Poston et al., 1962), the concept has not yet been applied to the analysis and control of processing plant operations. Several methods for tagging coal particles have been identified. These include magnetic, radioactive, and fluorescent techniques. As far as the magnetic tagging of coal particles is concerned, a method has been developed to manufacture synthetic magnetic particles of various sizes and specific gravities. Ideally the synthetic particles would have identical size and density as the coal particles being separated.

Jan 1, 1988

By J. R. Woolsey, B. G. Noakes

A prototype remote placer drill (RPD) has been designed and successfully tested in the offshore gold district of Nome, AK. The RPD system is unique in its design and in the cooperative support that was provided during its development by industry, academia and government. The RPD was conceived as a low-cost, rapid drill sampling system for the reconnaissance of marine precious metal placer deposits. The drill functions as a counter- f lush system. It incorporates a dual wall casing and a rotating percussion bit driven by way of a drill rod through the central eductor casing by a heavy duty pneumatic rock drill. The cost of drill sampling in the exploration of marine precious metal placers has traditionally been high due to the technical difficulties imposed by the environment and the remoteness of the sampling target. The objective was to reduce capital and operating costs of a drilling program through the development of a portable system incorporating drill compoments having a high power-weight ratio that could be deployed from work vessels of opportunity. A principal design requirement was to operate the system remotely from the sea floor with only flexible connections to the surface. This includes cable for deployment and retrieval and hoses for air supply and sample recovery, thus making the drill system semi-independent of the vessel's sea-induced motion. The prototype RPD underwent full operational test off Nome, AK in late summer 1988. It was deployed from the landing door of a modified LCT vessel, and rigged for a single pass of 5 m (16.5 ft). More than 50 holes were drilled in a wide variety of bottom materials typical of the off shore Nome submerged beach placers. The prototype RPD proved to be an overall success, recovering representative samples throughout the section in all but the heavy boulder ground. Compared with a conventional drill system on board that was assigned to a production drilling system, the RPD was capable of reliably sampling moderate ground less than 6 m (20 ft) in thickness, using a smaller crew and operating in higher sea conditions.

Jan 1, 1991

By Charles U. Keranen

The Tilden Mine is an iron ore mining, processing and pelletizing facility located on the Marquette Iron Range in Michigan's Upper Peninsula. It has a designed capacity to produce 8 million long tons of pellets annually from 21 million long tons of crude. It is a partnership owned by The Cleveland-Cliffs Iron Company, Algoma Steel Corporation, LTV Steel Corporation, the Steel Company of Canada, Wheeling Pitts- burgh Steel Corporation and the Sharon Steel Corporation. Cleveland- Cliffs manages and operates the Tilden. The crude ore averages 35% iron and is primarily non-magnetic iron oxide and silica. The major ore mineral is martite. Hematite, earthy hematite, goethite and magnetite are also present. The principal gangue mineral is chert. The ore grains are mostly in the 10 to 25 micron size range which necessitates very fine grinding for liberation. The concentrating process is the most complex one used in the iron ore industry. The unique technology for Tilden was developed in the mid and late 60's. The design and construction occurred in the early 70's and operation of the first phase which was of 4 MLTPY capacity began in October. 1974. Expansion of the facility to the current 8 MLTPY capacity was completed in 1979. Chemicals are the key to the beneficiation process at the Tilden Mine. The flowsheet utilizes selective flocculation - desliming, cationic silica flotation and concentrate dewatering by thickening and filtering. Nine different process chemcals are used. The control of the reagent feed systems is highly auto- mated. The entire concentrator is operated from a central control room. The concentrator flow diagram is presented in figure 1. The plant consists of 12 primary autogenous grinding lines, a common crushing circuit to handle an intermediate product within the primary grinding section, 24 pebble mill lines with cyclones and deslime thickeners, 12 flotation lines, 4 concentrate thickeners and slurry tanks, 8 lines of filters with six machines per line, and 2 tailings thickeners. A pumping system was installed in 1980 to permit the direct return of tailings thickener overflow water back to the reuse water pumphouse.

Jan 1, 1986

By David G. Chedgy

Noise control is an important consideration in the design and operation of coal preparation plants. It is essential to understand and control noise sources to provide a safe environment for operating personnel. The average noise exposure levels in a typical coal preparation plant generally range between 95 and 100 db. An operator should not be exposed to noise levels of this magnitude for more than 4 and 2 hr, respectively, according to MSHA (Mine Safety and Health Administration) regulations. The major noise sources in a coal preparation plant include noise from impacting the inside surfaces of steel chutes, vibrating screens, coal crushers, pumps, motors, fans, and blowers. The magnitude of noise varies considerably from one situation to another. NOISE EXPOSURE IN COAL PREPARATION PLANTS Noise regulations established by the Occupational Safety and Health administration (OSHA) are accepted by MSHA relative to caal preparation plants. Fig. 14-43 shows a graph of the time of noise exposure in hours per day to which a worker can be exposed for each A-weighted sound level. According to this graph, a worker is permitted to spend 8 hr in a 90-db noise environment, but that time must be halved when the A-weighted sound level increases 5 db. The noise dosage a worker receives is determined by the ratio of the length of time the worker spends in a particular noise environment divided by the length of time he is permitted to spend in that environment. If the worker is exposed to several different sound levels, his total dosage would be the sum of each of the individual dosages. The equation for determining the dosage is: where C is the actual duration of exposure at a given steady state noise level and T is the noise exposure limit for the level present during the time C According to MSHA regulations, the dosage, D, should not exceed one (1) for any worker for a full day of work. As an example of typical plant noise levels, vibratory screens and crushers emanate noise levels in excess of 90 db at a distance of 3 ft (0.9 m) with no material flow. With material flow, noise level increases 1 to 10 db depending

Jan 1, 1991

By John A. Cordes, John J. Schanz

INTRODUCTION The economic structures of industrialized countries require a continuous supply of reasonably priced and appropriately processed nonfuel minerals. As a result, national policy makers are sensitive to real or perceived threats to the effective operation of these commodity markets. Their most persistent concerns can be subsumed into the related political economy issues of supply availability and marketplace stability. These concerns are not new. For over a century the "global struggle" for mineral resources has influenced national policies and international relations (Eckes, 1979). During the past two decades the complexity of these issues, if not their place on national political agendas, has increased. Dramatic changes in the structure of mineral industries and in the nature of international economic relations have redefined policy needs and response options. This paper focuses on how selected OECD countries have responded to nonfuel mineral industry issues over the past twenty-five years. Particular emphasis is placed on the impact these policy decisions have had on the size and location of productive capacity and its utilization rates. The results, perhaps, are not surprising for this group of market- oriented economics. While individual cases of significant impact are easy to identify at various times in most countries, the overall importance of policy decisions has not been great. This is especially true for the past decade when excess capacity reached unusual highs of magnitude and duration. Macroeconomic forces and market structure changes played much more important roles. PERSPECTIVES ON THE ISSUES OECD nations dominate the international nonfuel minerals marketplace as producers, consumers and traders. In 1986, these twenty-four countries accounted for 75 percent of the Western world's export trade value in minerals, ores and metals. They imported 88 percent of the total value. During 1966, the respective percentages were 70 and 94. Japan was the world's largest importer in 1986 followed by the US, FRG, UK and France. The same five countries led the 1966 list except that, then, Japan was ranked fourth. Table 1 ranks the fifteen largest Western exporting nations in the two specified years. It also indicates the growth in current export dollars earned in 1986 compared to 1966.

Jan 1, 1989

The day after I reached New York, on January 30th, John Ryan of Anaconda told me where they wanted me to go. Late in 1916 the Russian Czar, desperate for money and supplies with which to carry on his unhappy share In the first World War, sent emissaries to the United States to see if our great mining companies might be interested in trying to find mines and to bring them to production in the millions of acres of the Imperial Estates in Russia and Siberia. It looked like a long chance as no one knew whether or where there might be important ore bodies. Even if they found them it might be a hopeless task to equip them under wartime conditions But the American copper companies had plenty of money and they were used to taking risks. They made a supersecret agreement with the Czar's deputies to send an exploring expedition to Russia at once I never learned the names of the other companies but Anaconda was to man- age the venture. Horace Winchell, then the leading mine geologist In the United States, was to be in charge of operations. Charles Janin, an eminent placer and dredge expert, was to study chances for producing gold and platinum. Though at 33 years of age I was much younger than the others, I was chosen to hunt for copper and other valuable metals. Charles Boynton, a business man who had lived in Russia and had married an attractive Russian woman, was to join the party and carry on any necessary financial or diplomatic affairs. He had gone on ahead to arrange for our reception Finally a graduate student from Ann Arbor named Steinberg was to go along as Interpreter. We soon found out that if his Russian was no better than his English his interpretlng couldn't be trusted too much I knew nothing about the millions of square miles In Russia and Siberia, and even less about what mineral deposits might be found, but I was delighted at the prospect. I was treading on air for the few

Jan 1, 1976

The "Gold" chapter of my adventures did not start with a rush. On May 14, 193 1, Thayer Lindsley wired me asking if I could examine the Pioneer mine in British Columbia right away. I replied, "Yes," but I had never heard of the Pioneer and, although many others were asking about gold during the Depression, none were doing anything about it. A little later another wire asked me to meet Gen. A.D. McRae in Vancouver in a couple of days. This was the start of 20 years of intermittent examinations for Lindsley. I took the train to Seattle and the night boat to Vancouver where I met Gen. McRae and his associate Victor Spencer. McRae had been one of the Canadian leaders during World War I and, for his services, he had been made a Canadian senator, a lifetime job. Col. Spencer was proprietor of a big store in Vancouver, and almost as distinguished. A seaplane was waiting for us in the harbor, to be piloted by Major McLaren, one of the leading Canadian flyers during the war. He flew us up the long fjord of Howe Sound and then on north along the route of the provincial-owned Pacific Great Eastern Railway past jagged snow-clad peaks to the village of Shalalth on Seton Lake. A rental car run by Curley Evans, a noted British Columbia character, was waiting for us in Shalalth and it took us for 50 miles over one of the steepest and crookedest roads I had ever seen. At the end of the road the Pioneer camp was set in a deep canyon in the Coast Range. Dave Sloan, another British Columbia character, was waiting for us and he immediately took me underground, at nine in the evening, to see the Pioneer ore. The ore body was then a small one but it was running over an ounce of gold per ton. The name Dave Sloan became synonymous with Pioneer. McRae and Spencer told me the history of Sloan arid the Pioneer on the way to the mine. The rich surface ore had first been discovered about 1879. It was then far inside the almost trackless wilderness of the beautiful

Jan 1, 1976

By A. E. Foscolos

British Petroleum (BP, 2005), indicates that world reserves for oil to be 1198 billion barrels, for natural gas the equivalent of 1156 billion barrels of oil and for coal the equivalent of 3219 billion barrels of oil. If we take into consideration the mean aver-age annual increase in demand of the last three years for oil, 2.6%, for natural gas, 3.9%, and for coal, 6.6%, then their respective reserves? lifespan are calculated to be 27, 34 and 38 years. Without taking into account their annual increase in demand, lifespan increases to 38, 67 and 161 years respectively. Since zero increase or perpetual increase in energy demands on finite resources is unrealistic the selection of the most suitable energy commodity for power generation rests upon the law of supply and demand of each commodity. This defines its price hence its selection for the production of cheap electricity. When the ratio of supply to demand is less than one, peak production is achieved. Any further increase in demand results in price increase to quench its demand. The Association for Oil and Gas Peak (ASPO) has calculated that when oil demand exceeds 84 million barrels/day, Peak Oil Production will be attained thus prices will start to increase in order to even demand with supply. Correspondingly, Gas Peak Production is expected to take place when demand exceeds 9.1 or 10.2 billion cubic meters/day. Peak Oil production has been calculated to take place in the current year, 2006, while Gas Peak production is estimated to take place between 2020 and 2025 provided that gas will not cover the energy deficit created from the lack of oil otherwise Gas Peak production could arrive as early as 2010. The use of coal for power generation is considered a better alternative than oil and gas if new combustion technologies with an energy efficiency of 43%, Germany, and 47%, Denmark, are adopted. These not only extend the lifespan of coal reserves but reduce also CO2 emissions by 25% and 31%, respectively. In the very near future CO2 sequestration and fixation in deep geological strata will eliminate its emissions thus rendering the use of coal the cheapest feedstock for power generation.

Jan 1, 2006

By Leonard W. III Joseph, William H. Buttermore

Noise control is an important consideration in the design and operation of coal preparation plants. It is essential to understand and control noise sources to provide a safe environment for operating personnel. The average noise exposure levels in a typical coal preparation plant generally range between 95 and 100 db. An operator should not be exposed to noise levels of this magnitude for more than 4 and 2 hr, respectively, according to MSHA (Mine Safety and Health Administration) regulations. The major noise sources in a coal preparation plant include noise from impacting the inside surfaces of steel chutes, vibrating screens, coal crushers, pumps, motors, fans, and blowers. The magnitude of noise varies considerably from one situation to another. NOISE EXPOSURE IN COAL PREPARATION PLANTS Noise regulations established by the Occupational Safety and Health and- ministration (OSHA) are accepted by MSHA relative to coal preparation plants. Fig. 14-43 shows a graph of the time of noise exposure in hours per day to which a worker can be exposed for each A-weighted sound level. According to this graph, a worker is permitted to spend 8 hr in a 90-db noise environment, but that time must be halved when the A-weighted sound level increases 5 db. The noise dosage a worker receives is determined by the ratio of the length of time the worker spends in a particular noise environment divided by the length of time he is permitted to spend in that environment. If the worker is exposed to several different sound levels, his total dosage would be the sum of each of the individual dosages. The equation for determining the dosage is: where C is the actual duration of exposure at a given steady state noise level and T is the noise exposure limit for the level present during the time C According to MSHA regulations, the dosage, D, should not exceed one (1) for any worker for a full day of work. As an example of typical plant noise levels, vibratory screens and crushers emanate noise levels in excess of 90 db at a distance of 3 ft (0.9 m) with no material flow. With material flow, noise level increases 1 to 10 db depending

Jan 1, 1991

By Thibaut Pannetier, Damien Rogat, Catherine Larive, André Regnard, David Chamoley

"INTRODUCTION For several decades, the use of fibre-reinforced sprayed concrete (FRSC) has been becoming increasingly widespread, either as a replacement for or in addition to traditional reinforcements. Macro-synthetic fibres appeared on the market at the same time as metal fibres (in the 1980s), but their use has developed more recently in France, starting in the early 2000s. While their properties are attractive for underground operations, their long-term performance remains the subject of some controversy, particularly with regard to the phenomenon of creep [1-5]. Unfortunately, the many differences of protocol among the studies carried out (materials, metering, spraying equipment and test methods, etc.) mean that, in general, the results cannot be compared. Although several methods have been developed to assess the bending creep behaviour of fibre-reinforced concrete, the majority of them test notched beams resting on isostatic supports. There are currently no standardised test methods adapted to FRSC on hyperstatic supports (as is the case for FRSC used for underground support). The Asquapro association has thus developed a new test specially designed for this type of concrete. Slabs of thickness 10cm, measuring 60 x 60 cm in plan have been sprayed and tested under bending stress according to a test procedure inspired by the standardised test of energy absorption capacity (NF EN 14488-5). An experimental campaign was launched in October 2014 to study the behaviour of seven types of sprayed concrete, manufactured using the same concrete matrix: six of them were reinforced with different metal or macrosynthetic fibres and the seventh with a welded wire mesh. Fourteen slabs were sprayed for each type of concrete and also for the non-reinforced concrete with the same matrix. The types of mechanical performances measured were the compressive strength and energy absorption capacity (at seven and twenty-eight days), in addition to the creep behaviour of these seven types of concrete, placed under stress on the seventh day. This article follows on from that published in the WTC 2015 congress proceedings [6]: the programme and the test methods are briefly described here and the results available at the time of writing are presented and discussed."

Jan 1, 2016

By F. Bruey

The Factorial Model Experimenters are often interested in systems that are multi-factorial. A multi-factorial system is one whose output is believed or known to be dependent on the particular settings of several inputs, or factors. We can think of these factors as defining a space, with each point in this space corresponding to a particular set of factor settings. Experimenting can be thought of as exploring this space - finding out how the response of the system changes as factor settings are changed. There are several challenges in this exploration, among which are deciding what region to explore, designing an experiment that explores it most effectively, and describing the results of the exploration. This paper deals principally with the last of these; it shows how the factorial model can be used to describe how the response of the system changes as factor settings are changed. A strength of the factorial model is that it treats the factors as causes of change in the system's response and focuses on relations among these causes. In particular, the factorial model focuses on whether causes act independently on the system (in a sense to be explained below), or whether they interact. This is important because the experimenter generally seeks to control the system, and because control based on causes that act independently of other causes is relatively simple, whereas control based on causes that interact is more challenging. Also, mapping the space - finding out how the response of the system changes as factor settings are changed - will require less work if, during the exploration, it can be determined which of the causes act independently. For the sake of example, let us assume that the space we are exploring is three-dimensional, and that we have already defined, for each of the three factors, the range of interest. Let us consider all the ways in which the response of the system might depend on the settings of these three factors. In the simplest case, the response in this region does not depend on any of the factors. The response is constant throughout the space, at say, 80 units.

Jan 1, 2007

By G. Plenge, M. Brittan

"Plant design parameters for gold extraction, leach residence time and cyanide consumption are generally determined from standard bench-scale bottle roll or agitation leach tests. The application of laboratory data to process design has essentially evolved from the testing of oxide or low cyanide-consuming ores. Such scale-up factors may not be appropriate for ores that deplete cyanide and oxygen since this interferes with gold extraction kinetics. High cyanide-consuming ores also exacerbate the differences between the conditions applicable to small batch tests and large continuous operations. Testing a reactive high-sulfide South American ore deposit necessitated the re-evaluation of conventional bench-scale cyanidation procedures. Pulp density can be a major factor affecting the results for plant design purposes and should be treated as a test work variable. As with high clay-bearing ore, where pulp viscosity can hinder mass transfer, minimizing the influence of test equipment on gold extraction kinetics may require low pulp densities. This introduces interpretative complexity since cyanide consumption changes as a function of pulp density. Activated carbon also consumes cyanide, so its effect has to be accounted for in the case of carbon-in-leach (CIL) or carbon-in-pulp (CIP) plant flowsheets. Since cyanide is an expensive reagent, often a major component of plant operating costs, it is important that the scale-up of cyanide consumption from laboratory to plant be representative. The traditional method of reporting cyanide consumption in bench-scale testing is questioned since it takes credit for residual free cyanide in leach tails. The projected plant consumption may be better estimated by using the total cyanide addition in a laboratory test. We propose a test work protocol that categorizes the cyanide consumption into its components but requires more extensive testing to generate design data. The ultimate validation of scale-up factors used by project engineers requires rigorous bench-scale versus commercial plant comparative data. Such data are not readily available.IntroductionMajor factors in the design of a gold processing plant are gold recovery, leach residence time and cyanide consumption. These parameters are important determinants of project revenue and costs and, thereby, potentially of project financial viability. Estimates of the associated design criteria for a commercial plant are normally generated from laboratory cyanidation, carbon-in-leach (CIL) or carbon-in-pulp (CIP) tests using standard procedures (Angove, 2005). The key question is whether the standard laboratory test work procedures developed historically for low reagent consuming ores are appropriate for ores that are highcyanide and oxygen consumers.The present paper examines test procedural factors that can influence the test work results and, therefore, their interpretation for design scale-up purposes. The study refers in particular to a high cyanide-consuming sulfide ore. The ore was being tested to develop scoping level engineering design criteria for a proposed project in South America."

Jan 1, 2015

By J. -B. C. Varnier, J. A. Cremeens, D. D. Overton

"Slope failures that occurred in 2008 and 2009 at the Pikeview Quarry in El Paso County in Colorado in the United States were investigated using three-dimensional discrete element modeling methods. Large-scale block sliding failures occurred along weak bedding planes that dip steeply into an excavation located at the toe of the slope. Several mining sequences at the toe of the slope were simulated to evaluate the effects of various degrees of extraction and backfill on slope stability. Slope stability back-analysis was conducted using prefailure and post-failure conditions to determine the joint shear strength properties. Laboratory testing was also conducted to determine intact rock properties. Three-dimensional discrete element analysis was uniquely applicable to this evaluation because it allowed representation of shear stress of the basal sliding surface and afforded evaluation of several scenarios of extraction and backfill at the toe of the slope. IntroductionThe Pikeview Quarry is an aggregate quarry located approximately 8 km (5 miles) northwest of Colorado Springs in El Paso County, CO, USA. The quarry has been operated by several owners since the early 1900s. According to the U.S. Mine Safety and Health Administration (MSHA, 1986), the quarry has been a major source of construction aggregate for the Colorado Springs area for many years. In the 1950s, the site was mined by Peter Kiewit and Sons to provide limestone for the construction of the nearby Air Force Academy.A large-scale slope failure occurred on Dec. 2, 2008, which stopped mining activity at the Pikeview Quarry. A second, related slope failure occurred on Sept. 13, 2009. The second slope failure was located immediately adjacent to the initial December 2008 failure.The objective of this paper is to discuss the three-dimensional slope stability evaluation. The causal relationships of slope instability are not within the scope of this publication. However, omitting the precursors to slope failure would limit understanding of the nature of the slope stability evaluation. The regional and local geology and the history of slope instability at the Pikeview Quarry aid in understanding these precursors. Two main failure mechanisms were hypothesized during the failure investigation to explain the triggering of the 2008 and 2009 large slope failures at the Pikeview Quarry, and both of these mechanisms were given equal credence in the present study. Quarry excavation and backfilling was a key factor in the slope instability for both failure mechanisms. The excavation was backfilled in stages in an effort to provide slope support. The objective of the three-dimensional model was to evaluate the effects of extraction and backfill at the toe of the slope with respect to slope stability."

Jan 3, 2018

By C. Newman

"As underground mining continues to operate at deeper depths and in more complex multiple seam mining geometries there has been an increased demand for higher design standards in ground control safety and stability within the mining industry. For the past 20 years, NIOSH has developed and validated a number of software tools to aid in the development of safer mining environments with respect to improved roof support performance, pillar stability in longwall and room and pillar mines, formation characterization, the prediction of roof conditions, etc. These tools are available, free of charge, to the mining industry as stand-alone software packages. As cloud computing gains momentum, there is a definite need to develop internet based applications for mine design that would be easily accessible to any user at any time, including underground where permitted. This paper introduces a new web-based product which will allow for faster and easier access to existing ground control designs, on-the-fly calculations in the field as needed, and instant online collaboration between operations personnel and planning engineers. It is expected that the industry will rapidly embrace this product and, as it is common with all new innovative technologies, it will be a new paradigm for mining engineering computer applications. INTRODUCTION Since its release to the public in the late 1980's, the World Wide Web has drastically changed from a collection of static HTML web pages to a dynamic vehicle driving e-commerce, collaborative working relationships, and the mass distribution of information and media (Offutt, 2002). Recent developments in Internet capabilities, such as Cloud Computing and Software as a Service, have begun a migration away from desktop-based software in adoption of the web application (Hayes, 2008). Web applications, or web apps, are designed on the client-server architecture paradigm in which the client, or user, can interact with an application through web browsers without disrupting or installing software on potentially thousands of client computers (Nations, 2015). Currently, web-based software applications are being utilized in all business sectors and markets from commerce, finance, media, and even engineering. In fact, the Alabama Department of Transportation has developed a web-based geotechnical geographical information system (GeoGIS) for the management of and access to geotechnical and subsurface data for transportation projects across the state (Graettinger, et al., 2001). Similarly, Dyno Noble has developed a service application for explosive engineers. The Explosives Engineers' Guide application equips users with a full range of product information as well as on-demand blasting calculations for powder factor, airblast prediction, ground vibration, etc. Through the incorporation of a web server, one is able to utilize the functionality of the desktop-based software through a web browser located on any personal computer, tablet, or Smartphone (Vaughan-Nichols, 2002)."

Jan 1, 2016

By Ralph J. Holmes

INTRODUCTION Although sampling techniques used by the mineral industry continue to improve, sampling is still an area which is often neglected. Frequently, sampling and sample preparation requirements are left to personnel who do not fully appreciate the significance and importance of sampling. Consequently, plant evaluations are often based on seriously biased samples, leading to mass balance problems and incorrect assessments of plant performance. The basic rule for correct sampling is that each particle of ore or concentrate must have an equal probability of being collected and becoming part of the final sample for analysis. If this is not the case, bias is easily introduced and the sample is not representative. For example, when ore is travelling on a conveyor belt, the lumps may come to the surface. Consequently, a grab sample taken from the top layers only will contain a greater proportion of lumps, i.e., the sample is biased. There seems little point in making major investments in precise analytical equipment, if the sample provided to the analytical laboratory is not representative in the first place. This paper describes the sources of plant sampling errors, reviews the methods of estimating their variance, presents some worked examples, and provides some practical advice for reducing sampling errors and their variance. SAMPLING BASICS It is generally accepted that the discharge point of an ore or concentrate stream is the most suitable sampling location. The stream can be intersected at regular intervals, and representative samples, referred to as increments, can be obtained by taking a complete cross-section of the ore stream. On the other hand, sampling devices that take part of the stream on an intermittent or continuous basis, e.g., a bleed from a pipe, may introduce serious bias, and should be avoided at all cost. Increments may be taken at completely random times or tonnages during the sampling operation, in which case it is called "random sampling". However, as shown below, random sampling results in the largest sampling variance, so it is preferable to divide the ore or concentrate stream up into strata of equal time or mass and take one increment from each stratum. This operation is called stratified sampling and may be either systematic sampling, in which increments are taken at the same point in each stratum, or stratified random sampling in which the increments are taken at random within each stratum. Systematic sampling results in the smallest sampling variance, provided periodic variations in quality or quantity are not present which may coincide with, or approximate to, any multiples of the proposed sampling interval. In such cases, it is strongly recommended that stratified random sampling within fixed time or mass intervals be carried out.

Jan 1, 1991

By Ben Benally, Joseph M. Hans

INTRODUCTION The decontamination of the former Shiprock uranium millsite and the interim stabilization of its tailings piles began in March 1974, and ended in June 1978. Personnel monitoring for whole body gamma ray exposure was conducted for selected individuals working at the mill site throughout most of this period. The millsite and exposure conditions are briefly described to develop a basis for interpretation of the exposure data. Millsite The Shiprock uranium millsite is located in the community of Shiprock, New Mexico on a bench overlooking the San Juan River (Figure 1). Both Shiprock and the millsite are located on the Navajo Indian Reservation. About 1.5 million tons of tailings were produced on the millsite during its operation from 1954 to 1963. The tailings were pulped with waste process fluids and water, and discharged to form two tailings piles. The piles (ponds, dams) were formed with earth starter dikes and the dikes were then raised using the separated sand fraction of the tailings. The slime fraction of the tailings were discharged into the diked impoundment. The mill was shut down and partially dismantled before the lease expired in 1973, and the remainder of the mill and tailings reverted back to the Navajo Tribe which was the lessor. Portions of the millsite were then occupied by the Navajo Engineering and Construction Authority (NECA), a tribal enterprise. In addition to its regular activities, NECA established an on-site training school for heavy equipment operators. The trainees principally used the south tailings pile as a practice area and spread the tailings into a 10 hectare row of raffinate ponds located along the southwest side of the millsite. Overall, the training activities inceased the effective area of the tailings piles from 20 to 35 hectares. Another 56 hectares were contaminated with wind and water eroded tailings. Exposure Conditions Persons decontaminating a millsite may be subject to radiation exposures from several sources. Only whole body gamma exposures are discussed in this report. These exposures are arbitrarily divided into three levels: high, intermediate, and low. The levels are related to areas in which the decontamination work was being done and have no connotation concerning imminent hazards. High exposures would result when persons were working with raw tailings, and intermediate exposures would occur when persons were working in the ore storage and mill yards. Low exposures would result from working in areas where surface contamination exists from wind and water erosion. [ ] The millsite and its contaminated environs were divided into major areas to facilitate the decontamination work (Figure 2). Areas A, B, and C are defined as perimeter areas containing surface contamination. Work in these areas was expected to result in low exposures. Areas D, E, and F are the

Jan 1, 1981

By Jim Dunn

For decades many of us who are associated with the mineral industry have tried to show the public its economic and strategic importance. Some of the mineral industry's proponents have been politically powerful figures and have been widely quoted. Yet, as measured by public opinion, legislative support, or almost any other standard, our efforts have been inadequate. It is apparent that a set of environmental beliefs that discredit industry, firmly held by a number of idealistic persons, has had wider coverage in the media and in schools than has the mineral industry's message. Although the fervor of our idealistic friends is often unfounded and, their stands unscientific, they must be considered seriously. Unless we address the issues in terms the idealists will understand, the mineral industry will have little influence on them or on the general public. A. striking thing is that, quite often, translation of idealists' views into action has been counterproductive. The reason is obvious. Excessive amounts of money and energy have been spent on relatively minor problems. The common result is that larger problems have been created. It may be possible to help anti-industry idealists understand their own dependence on minerals, and thus render their views more realistic, if they are shown more effective ways to reach their stated goals. If those goals can be shown to be held in common by all sensitive human beings -- including those in business and industry - the dialogue becomes one of how to achieve common ends. Individual mining companies acting by themselves have little possibility of success, and companies working in unison through trade associations have not been successful. Further, it is unlikely that industry in general can be successful in changing minds unless it seeks outside help. But friends among those who influence public opinion have been hard to find. Historically, help from media has proven difficult to get. Nor has enough help from educators been forthcoming. Yet, a war is going on in the technological, philosophical, and political trenches, even though much of the public is not aware of it. For the first time in years, there is row a significant and growing number of eloquent and brilliant thinkers on the side of free enterprise and industry, many of them environmentalists, but without the anti-industry mind-set. They have had remarkably little help from the private sector or even from the present administration. Industry may do far more for itself in the long run by encouraging these brave but bruised individuals and their organizations than by trying to work alone. These friends of free enterprise are working against a seemingly stacked deck relative to much of the media, the bureaucracy, and the educational system. However, despite their problems, their success to date has been remarkable. With more cooperation from industry they should do even better.

Jan 1, 1987

By Verya Nasri, Heather M. Ivory, Kevin Clarke, Eric Cole

Development of the New York City Water Supply System The New York City water supply system serves a population of almost nine million, including residents in neighboring counties. Peak day demands on the system are currently running at about 70 m3/sec (about 1,600 mgd), which is significantly lower than in the 1990s. This trend of reducing demands over the past 25 years, which has been experienced in other major urban centers in the US, is mainly the result of conservation measures and increased cost consciousness on the part of water users. In the long term, demands are expected to once again follow an increasing trend with population growth, so that by the end of the planning horizon of these studies, the year2045, the peak day demand is expected to increase to about 85 m3/sec (2,000 mgd).The system is served largely by surface water sources, regulated by a system of 19reservoirs and three controlled lakes, which are connected to the City by a series of aqueducts, the longest of which is about 87 km (54 miles). The total storage in the sys-tem amounts to about 560 billion gallons, providing a system firm yield of about1300 mgd. The Delaware system provides about 50% of the City’s water, the Catskill about 40%, with the remaining 10% provided by the Croton. The system as a whole, which is shown on Figure 1, has been built up over the past 150 years, and is truly a marvel of engineering. The Catskill and Delaware aqueducts both discharge into Kensico Reservoir, which is a daily balancing reservoir located in Westchester County about 24 km(15 miles) north of the New York City line. The two aqueducts extend south for a further 14 miles to combine again at Hillview Reservoir in the Bronx, which provides hourly balancing storage for New York City system. The Croton aqueduct runs nearby as shown on Figure 2, but does not connect into the two reservoirs. From Hillview Reservoir the water is supplied to the city via three main distribution tunnels, known as City Tunnels 1, 2, and 3. City Tunnel No.1 was developed in the 1920s as part of the Catskill system. City Tunnel No. 2 followed in the 1960s as part of the Delaware system. City Tunnel No. 3 (CT3) is partly under construction and partly in operation, and is being implemented to permit the other distribution tunnels to be taken out of operation for the first time for inspection and maintenance. Presently CT3 is supplied with water from Hillview Reservoir via a large underground valve chamber, the Van

Jan 1, 2007

Ten years ago, only 3% of Consol's underground coal production resulted from using the longwall mining method. Today, that figure has grown to 45% and has helped the Pittsburgh-based concern fuel an upswing in productivity. The company reported that productivity at its underground mines, excluding labor strike periods, increased 24% between 1978 and 1981. Last year, an additional 8% increase was achieved. Efforts such as improved safety, training, engineering, and maintenance programs as well as the closing of unproductive mines has contributed to these gains, according to Joseph M. Richards, Consol's executive vice president of operations. But, Richards adds, a great part of the credit goes to longwall mining. What is Longwall Mining? To fully appreciate the advantages of longwall, one needs an understanding of how mining is done by other methods. For instance, in both conventional and continuous mining, rooms or tunnels are dug in the coal seam. Pillars of coal are left standing to support the roof as mining moves forward in the seam. In conventional mining, a slot is cut in the base of the seam and holes for blasting are drilled. After blasting, the coal is loaded. A more efficient method - continuous mining - uses a machine that combines cutting and loading. Longwall mining, by contrast, works backwards from the end of a panel. Two parallel sets of tunnels (development panels) are cut into a seam with continuous mining machines, then connected with a set of crosscuts at the far end. Min¬ing then proceeds back toward the entrance. Longwall mining employs some very productive machines. Large drum shearers, for example, run on a track along the length of the coal face for some 150-180 m (500-600 ft). The shearers cut the coal which falls onto a conveyor system or pan that also runs the entire length of the face. The longwall crew works under a roof of heavy steel supports called shields. As the coal is removed, shearers, pans, and shields are moved forward by hydraulic rams. The roof is allowed to collapse behind the shields. In addition to increasing production, longwall mining is considered to be safer because the miners work under strong steel shields. New designs have made them more rugged and maintenance free, as well as more stable on soft mine floors. Early roof supports, called chocks, had gaps in the roof canopies. The new roof shields now cover the entire working area and are better able to prevent roof material from falling into the working area, thereby improving safety and productivity. Longwall mining also results in a cleaner product in many mines. If the first layer of rock over the coal seam is thin, it might have to be removed with the coal in a room-and-pillar operation so a

Jan 11, 1983